000
AXNT20 KNHC 171155
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
705 AM EST THU FEB 17 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF 
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE 
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE 
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND 
RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ...
THE ITCZ IS ANALYZED FROM W AFRICA NEAR 5N7W ALONG 3N17W 2N24W 
THEN CROSSING THE EQUATOR NEAR 36W. CLUSTERS OF SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE EQUATOR TO 3N 
BETWEEN THE PRIME MERIDIAN AND 16W AND FROM 4N TO S OF THE 
EQUATOR BETWEEN 19W-28W. 

...DISCUSSION...

GULF OF MEXICO...
A SURFACE RIDGE COVERS THE E CONUS AND THE GULF ANCHORED BY A 
1029 MB HIGH IN THE W ATLC. A BROAD UPPER RIDGE EXTENDS ALONG 
THE COAST OF MEXICO TO OVER TEXAS COVERING THE W GULF WHILE AN 
UPPER TROUGH CONTINUES TO MOVE INTO THE W ATLC GIVING THE GULF W 
TO NW FLOW ALOFT. STRONG SUBSIDENCE AND DRY STABLE AIR DOMINATES 
THE GULF BASIN LEAVING THE AREA WITH MOSTLY FAIR CONDITIONS THIS 
MORNING. RETURN FLOW AROUND THE SURFACE RIDGE IS GIVING THE W 
GULF SOUTHERLY FLOW WHICH IS BANKING LOW LEVEL CLOUDS OVER THE 
NW GULF TO INLAND OVER LOUISIANA AND TEXAS. HIGH PRESSURE RIDGE 
WILL REMAIN ACROSS THE NORTHERN GULF COAST THROUGH MON.

CARIBBEAN SEA...
REMNANT SURFACE MOISTURE REMAINS OVER THE NW CARIBBEAN FROM THE 
RECENT FRONTAL PASSAGE AND CONTINUES TO GENERATE SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 125 NM OF LINE FROM THE 
WINDWARD PASSAGE TO INLAND OVER HONDURAS NEAR 15N84W INCLUDING 
PORTIONS OF HAITI...E CUBA...JAMAICA...AND NE NICARAGUA. THE 
UPPER LEVELS ARE DOMINATED BY AN UPPER RIDGE ANCHORED IN THE W 
TROPICAL ATLC GIVING THE CARIBBEAN SW TO W FLOW ALOFT. THIS IS   
LEAVING THE REMAINDER OF THE CARIBBEAN WITH FAIR CONDITIONS 
AGAIN THIS MORNING WITH SOME ISOLATED SHOWERS USHERED IN ON THE 
TRADE WINDS. HIGH PRESSURE OVER THE W ATLC WILL DRIFT SLOWLY SE 
THROUGH SAT. TRADE WINDS WILL INCREASE LATE SAT THROUGH MON AS 
THE SURFACE RIDGE STRENGTHENS.

ATLANTIC OCEAN...
A SURFACE RIDGE COVERS THE W ATLC W OF 60W INTO GULF OF MEXICO 
ANCHORED BY A 1029 MB HIGH ABOUT 300 NM WNW OF BERMUDA. A BROAD 
UPPER TROUGH COVERS THE W ATLC INTO THE CENTRAL ATLC W OF 40W 
SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N38W 
EXTENDING TO 23N56W WHERE IT BECOMES A SURFACE TROUGH TO 21N66W. 
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 
75 NM E OF THE FRONT N OF 28N AND WITHIN 30 NM E OF THE 
REMAINDER OF THE COLD FRONT. ISOLATED SHOWERS ARE WITHIN 75 NM 
EITHER SIDE OF THE SURFACE TROUGH. A SURFACE RIDGE COVERS THE 
REMAINDER OF THE CENTRAL ATLC INTO THE E ATLC ANCHORED BY A 1022 
MB HIGH NEAR 27N25W GIVING THE AREA E OF THE FRONT FAIR 
CONDITIONS THIS MORNING. 

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW